Exceptionally large, euhedral crystals with pronounced radioactivity. Polished section microprobe analysis indicates a high degree of homogeneity. Th content is 8-16 weight percent.
Habit:
Tabular, Monoclinic, Masses to 2.4 kg
Colour:
Brick-red, Brown, Tan
Luminescent properties:
None
Quality for species:
Excellent - world class for species or very significant. (!!)
Cactus Jack pegmatite, Burnet County, Texas, USA